• Bulletin of the Korean Chemical Society
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• v.35 no.3
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• pp.705-708
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• 2014

We demonstrate the blue InGaN/GaN multiple quantum wells light-emitting diodes (LEDs) with an embedded air-gap photonic crystal (PC) which was fabricated by the lateral epitaxial overgrowth of GaN layer on the tungsten (W) nano-masks. The periodic air-gap PC was formed by the chemical reaction of hydrogen with GaN on the W nano-mask. The optical output power of LEDs with an air-gap PC was increased by 26% compared to LEDs without an air-gap PC. The enhanced optical output power was attributed to the improvement in internal quantum efficiency and light extraction efficiency by the air-gap PC embedded in GaN layer.

• Journal of the Optical Society of Korea
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• v.6 no.3
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• pp.59-71
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• 2002

Photonic band gap structures have a high potential for nearly zero-threshold lasers. This paper describes new-types of low-threshold photonic crystal lasers fabricated in InGaAsP slab waveguides free-standing in air. Two-types of photonic crystal lasers are studied. One is a single-cell nano-cavity laser formed in a square array of air holes. This photonic band gap laser operates in the smallest possible whispering gallery mode with a theoretical Q >30000 and exhibits low threshold pump power of 0.8 mW at room temperature. The nther laser does not have any cavity structure and the lasing operation originates from the enhanced optical density of states near photonic band edges. A very low threshold of 35 $\mu$W (incident pump power) is achieved from this laser at 80 K, one of the lowest values ever reported. This low threshold is benefited from low optical losses as well as enhanced material gain at low temperature.

• Korean Journal of Optics and Photonics
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• v.20 no.4
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• pp.211-216
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• 2009

Much research into two-dimensional (2-D) photonic crystal (PC) structures has been conducted for realization of ultrasmall optical integrated circuits. A 2-D silicon (Si) PC slab structure with air cladding (n=1) is one of the representative structures in 2-D PCs. While air-clad Si PC slab structures have good optical characteristics, their suspension in air can lead to mechanical weakness, making integration with some optical devices difficult. In this paper, we propose improving the mechanical robustness of PC structure by developing a 2-D Si PC structure with symmetric silica cladding (n=1.44) and comparing its optical properties to that of the air-clad structure. First, we investigate the optical properties of a 2-D Si PC slab structure with air cladding by using a 3-D finite difference time domain method. We determined that a photonic bandgap of 330 nm and a non-leaky propagating bandwidth of 100 nm in the optical communication range are possible. Next, we investigate the optical properties of 2-D Si PC slab structures with silica cladding. Even though the refractive index of the silica cladding is higher than that of air, we developed a silica-clad structure with good optical properties: a photonic band gap of approximately 230 nm and a non-leaky propagating bandwidth of 90 nm, comparable to that of the air-clad PC structures.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.374-375
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• 2006

Three-dimensional artificial crystals with periodicity corresponding to terahertz wave lengths were fabricated by self-assembling monosized metal spherical particles. The metal crystals were weakly sintered to utilize them as templates. The metal templates were inverted to air spheres crystal embedded in dielectric resin though infiltration and etching. The resulting resin inverted crystals clearly presented the photonic stop gaps within terahertz wave region and the frequencies of the gaps were confirmed to agree well with calculation by plane wave expansion method.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.11a
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• pp.120-123
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• 2002

In this study it had an excellent optical characteristic, it followed in the creation rate and the refractive index regulation to the ease. Chalcogenide produced the $As_{45}Se_{45}Te_{10}$ thin film and the $MgF_{2}$ thin film. It measured thin film plan simulation, and the thin film has a 1 -dimensional photonic band gap. The chalcogenide $As_{45}Se_{45}Te_{10}$ thin film was measured with the fact that it has a high refractive index (2.6~2.9). The $As_{45}Se_{45}Te_{10}$ and $MgF_{2}$ thin film, have a high refractive index and a low refractive index, it used a simulation and planed period 5-pairs structure, the result was from 500nm to 800nm. It will be able to confirm the characteristic which most of the incidence light reflects, the He-Ne (632.8nm) laser was irradiated in the thin film which stabilized the thin film. $As_{45}Se_{45}Te_{10}$ (high refractive index layer: H) and $MgF_{2}$ (low refractive index layer: L) results which plans the thin film with glass/LHLHLLHLHL/air structure, 632.8nm against transmitance, increased a lot. An application possibility with the filter against a specific wave length was confirmed.

• Journal of the Korea Convergence Society
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• v.12 no.2
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• pp.29-34
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• 2021

In this paper, a cylindrical photonic crystal waveguide with a low-index core is first proposed. The core can be filled with air, liquid, or arbitrary dielectric materials. Exact analyses for the electromagnetic field characteristics of guided modes, by using appropriate Bessel functions and applying the boundary conditions, are performed to find out the guiding characteristics of the proposed waveguide. For verification and usage in design and manufacturing process, the computer-calculation of the waveguide transmission characteristics is also performed by applying the rigorous full-vectorial finite difference method. Providing variations of the effective area for the fundamental mode of the designed waveguide with different numbers of cladding layers, ranging from 2.6056 ㎛2 to 5.9673 ㎛2 over the operation wavelength, generally as the core refractive index n1 is higher, the mode area becomes smaller and the result leads to more optimistic effect for nonlinear device applications.